/*
 * Licensed to Crate.io GmbH ("Crate") under one or more contributor
 * license agreements.  See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.  Crate licenses
 * this file to you under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.  You may
 * obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial agreement.
 */

package io.crate.expression.scalar;

import io.crate.data.Input;
import io.crate.metadata.FunctionType;
import io.crate.metadata.Functions;
import io.crate.metadata.NodeContext;
import io.crate.metadata.Scalar;
import io.crate.metadata.TransactionContext;
import io.crate.metadata.functions.BoundSignature;
import io.crate.metadata.functions.Signature;
import io.crate.types.DataTypes;

public class ConcatWsFunction extends Scalar<String, String> {
    public static final String NAME = "concat_ws";

    public static void register(Functions.Builder module) {
        module.add(
            Signature.builder(NAME, FunctionType.SCALAR)
                .argumentTypes(DataTypes.STRING.getTypeSignature())
                .returnType(DataTypes.STRING.getTypeSignature())
                .features(Feature.DETERMINISTIC)
                .setVariableArity(true)
                .build(),
            ConcatWsFunction::new
        );
    }

    ConcatWsFunction(Signature signature, BoundSignature boundSignature) {
        super(signature, boundSignature);
    }

    @Override
    @SafeVarargs
    public final String evaluate(TransactionContext txnCtx, NodeContext nodeCtx, Input<String> ... args) {
        String separator = args[0].value();
        if (separator == null) {
            return null;
        }

        StringBuilder sb = new StringBuilder();

        boolean firstNonNullProcessed = false;
        for (int i = 1; i < args.length; i++) {
            String value = (String) args[i].value();
            if (value != null) {
                if (!firstNonNullProcessed) {
                    firstNonNullProcessed = true;
                    sb.append(value);
                } else {
                    sb.append(separator).append(value);
                }
            }
        }
        return sb.toString();
    }
}
